JP3604294B2 - Fuel injection pump - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a fuel injection pump provided with a deflector.
[0002]
[Prior art]
Generally, a fuel injection pump includes a cylindrical pump body, a cylindrical barrel inserted and fixed in the pump body, and a plunger slidably provided in the barrel. Then, when the suction / discharge port formed in the barrel is closed, the fuel in the fuel pressurizing chamber is pressurized. Then, the pressurized fuel is sent under pressure to the fuel injection nozzle, from which it is injected into the combustion chamber of the engine. After the plunger closes the suction / discharge port, the plunger further moves forward, and when the lead formed on the outer peripheral surface thereof faces the suction / discharge port, fuel in the fuel pressurization chamber is formed between the pump body and the barrel through the suction / discharge port. Is discharged into the fuel pool. Thereby, the substantial fuel pressurization ends, and the fuel injection ends. Conversely, when the plunger returns, the fuel in the fuel reservoir is introduced into the fuel pressurized chamber through the suction / discharge port (see Japanese Utility Model Publication No. 4-29085).
[0003]
When the fuel in the fuel pressurized chamber is discharged from the suction / discharge port into the fuel reservoir, high-pressure fuel is ejected at a high speed, so that cavitation occurs, and the inner peripheral surface of the pump body facing the suction / discharge port, the suction / discharge port, Cavitation erosion may occur on the inner peripheral surface or the like. Therefore, a deflector is provided in the suction / discharge port to prevent cavitation.
[0004]
By the way, a pressing force by high-pressure fuel acts on the deflector attached to the suction / discharge port. In particular, a large pressing force acts on a large-sized fuel injection pump such as a marine fuel injection pump. In such a fuel injection pump, a screw hole is formed in an opening outside the suction / discharge port (outer peripheral side of the barrel), and a deflector is screwed and fixed to the screw hole. As a result, a large amount of pressing force acting on the deflector can be received.
[0005]
However, when the deflector is screwed and fixed, not only does the barrel expand and contract with the pressure fluctuation of the fuel pressurizing chamber, but also the fuel temperature difference between when the fuel injection pump is operating and when it is stopped (about 180 °). C), the screwed state between the deflector and the screw hole may be loosened over time. Therefore, by connecting the deflectors (usually, two suction ports and two deflectors are provided at 180 ° apart in the circumferential direction of the barrel) by a steel wire, even if the deflectors are loosened, the rotation of the deflectors is prevented. The deflector can be blocked, thereby preventing the deflector from coming out of the suction / discharge port.
[0006]
[Problems to be solved by the invention]
In the conventional fuel injection pump in which the deflectors are connected to each other by a steel wire, there is a problem that it is very difficult to replace the deflector at the site where the fuel injection pump is installed.
That is, when connecting the deflector and the steel wire, usually, the steel wire is inserted into a through hole formed in the deflector, and the distal end thereof is bent. Therefore, when replacing the deflector, it is necessary to straighten the bent steel wire, and after the replacement, it is necessary to insert and bend another steel wire. Such a work can be performed relatively easily in a factory equipped with facilities, but it must be performed manually at a site where a fuel injection pump without facilities is installed, which is very difficult.
In addition, since the steel wire connecting the deflectors is wound around a half circumference of the barrel, the steel wire cannot be replaced without removing the barrel from the pump body. Therefore, when replacing the deflector, the fuel injection pump must be disassembled, and there has been a problem that the operation requires a lot of labor and time.
[0007]
[Means for Solving the Problems]
In order to solve the above problem, the invention according to claim 1 includes a pump body, a cylindrical barrel attached to the pump body, and a plunger slidably provided in the barrel. In the fuel injection pump in which the barrel is formed with a suction / discharge port penetrating the peripheral wall portion, and a deflector is screwed and fixed to the suction / discharge port, an annular groove is formed on an inner circumferential surface of an outer end of the suction / discharge port. The outer periphery of a C-shaped snap ring whose diameter can be enlarged and reduced is removably fitted to the annular groove by expanding and contracting the snap ring itself, and when the deflector comes out of the opening outside the suction / discharge port, the snap ring is closed. by such outer end face of the deflector abuts against the inner peripheral portion, rotating in the direction escaping to the outside from the intake port of the deflector It is characterized in that the stop.
In this case, it is desirable that engagement holes for engaging a jig for reducing the diameter of the snap ring be formed at both ends of the snap ring.
In addition, a mounting hole that penetrates the wall of the pump body facing the suction / discharge port is formed, and a sealing member that seals the mounting hole is detachably attached to the mounting hole. The size is desirably set so that the deflector and the snap ring can pass through the inside thereof, and the jig can be inserted from the outside.
Further, it is desirable that the sealing member is a second deflector.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment in which the present invention is applied to a fuel injection pump 1 used for marine and other large diesel engines will be described with reference to FIGS. The present invention is also applicable to a fuel injection pump used for a small or medium-sized diesel engine.
[0009]
As shown in FIG. 3, the fuel injection pump 1 includes a pump body 2. The pump body 2 has a cylindrical shape with upper and lower ends opened. A delivery valve seat 3 is fixed to an upper end surface of the pump body 2 with bolts B. The delivery valve holder 4 is fixed by bolts B.
[0010]
A barrel 5 is removably inserted inside the pump body 2. The barrel 5 is fitted to the pump main body 2 so as to be non-rotatable and movable in the axial direction (vertical direction), and has a lower end rotatably and vertically movable in the pump main body 2. The sleeve S1 that has been improperly fitted is screwed. Therefore, when the sleeve S1 is rotated by the control rack L1, the barrel 5 is vertically displaced. A plunger insertion hole 5a extending from the lower end surface to the upper end surface is formed at the center of the barrel 5, whereby the barrel 5 is formed in a cylindrical shape. In the middle portion of the barrel 5, two suction / discharge ports 5b extending from the outer peripheral surface to the inner peripheral surface of the plunger insertion hole 5a are formed. The two suction / discharge ports 5b are arranged at the same position in the axial direction of the barrel 5 and 180 ° apart in the circumferential direction. Only one suction / discharge port 5b may be formed.
[0011]
The plunger 7 is slidably inserted into the plunger insertion hole 5a. The plunger 7 is urged downward by a spring (not shown), and the lower end of the plunger 7 is pressed against a cam portion of a cam shaft (not shown). Therefore, when the camshaft is rotationally driven by an engine (not shown), the plunger 7 reciprocates in the up-down direction following the rotation. When the plunger 7 closes the suction / discharge port 5b during the upward movement of the plunger 7, the fuel in the fuel pressurizing chamber 8 is pressurized. The pressurized fuel pushes and opens the valve 9, is pressure-fed from a discharge port 10 to a fuel injection nozzle (not shown), and is injected into a combustion chamber of the engine. When the plunger 7 further moves forward and the lead 7a formed on the outer peripheral surface of the plunger 7 faces the suction / discharge port 5b, the fuel in the fuel pressurizing chamber 8 is filled with the vertical groove 7b formed on the outer peripheral surface of the plunger 7, The fuel is discharged to the fuel reservoir 11 through the suction / discharge port 5b . As a result, the substantial pressurization of the fuel by the plunger 7 ends, and the fuel injection ends. Conversely, when the plunger 7 moves backward, the fuel in the fuel pool 11 is introduced into the fuel pressurizing chamber 8 through the suction / discharge port 5b . The fuel reservoir 11 is formed annularly between the inner peripheral surface of the pump body 2 and the outer peripheral surface of the barrel 5, so that fuel supplied from a feed pump (not shown) circulates. I have.
[0012]
Here, when the barrel 5 is vertically displaced by the control rack L1 and the sleeve S1, the stroke from when the plunger 7 starts to move forward to when the suction / discharge port 5b is closed to start pressurizing the fuel, that is, the prestroke changes. . Further, when the plunger 7 is rotationally displaced via the sleeve S2 by the control rack L2, the position of the lead 7a facing the suction / discharge port 5b changes, whereby the fuel injection amount can be changed.
[0013]
The intake / exhaust port 5b is provided with a deflector 12 for preventing cavitation. That is, as shown in FIG. 1 and FIG. 2, the suction / discharge port 5b has a straight hole portion 5d, a first tapered hole portion 5e, and a second tapered hole portion 5f which are sequentially formed from the plunger insertion hole 5a side toward the outside. And a screw hole 5g, and the holes 5d to 5g are formed concentrically. The small end diameter of the first tapered hole 5e is the same as the inside diameter of the straight hole 5d, and the large end of the first tapered hole 5e is the same as the small end of the second tapered hole 5f. The inner diameter of the screw hole 5g is larger than the large end diameter of the second tapered hole 5f.
[0014]
On the other hand, the deflector 12 includes a main body 12a and a rod-like projection 12b formed at the center of the distal end surface. The main body 12a is screwed into the screw hole 5g, and the deflector 12 is fixed to the outer end of the suction / discharge port 5b by pressing the tip surface of the main body 12a against the bottom surface of the screw hole 5g. In order to rotate the main body 12a screwed into the screw hole 5g, a hexagonal wrench (not shown) is provided at the center of the protrusion 12c formed on the rear end face (outer end face) of the main body 12a. A wrench hole 12d for insertion is formed. Instead of the wrench hole 12d, the outer peripheral surface of the protrusion 12c may be formed in a hexagonal shape, and the deflector 12 may be rotated by a wrench with a hexagonal hole. On the other hand, the projection 12b has a first taper portion 12e on the distal end side and a second taper portion 12f on the proximal end side having a smaller taper angle than the first taper portion 12e, and both are formed concentrically. The first tapered portion 12e is located in the straight hole portion 5d, and the second tapered portion 12f extends from the second tapered hole portion 5f through the first tapered hole portion 5e to the straight hole portion 5d. Between the first and second tapered portions 12e and 12f, the straight hole portion 5d and the first and second tapered hole portions 5e and 5f, a gap for fuel flow is formed in an annular shape. Further, a plurality of through holes 12g through which fuel flows are formed in the main body 12a.
[0015]
An annular groove 5h is formed at an end outside the suction / discharge port 5b (on the outer peripheral side of the barrel 5). A snap ring 13 is mounted in the annular groove 5h. The snap ring 13 has a substantially C-shape, and can be expanded and contracted by elastically deforming both ends thereof so as to approach and separate. Moreover, in the reduced diameter state, the outer peripheral portion of the snap ring 13 can be inserted into the suction / discharge port 5b from the opening outside thereof. Fit into the annular groove 5h. As a result, the position of the snap ring 13 is fixed. The inner peripheral portion of the snap ring 13 protrudes from the annular groove 5h, and almost contacts the rear end surface of the main body 5a. Therefore, when the screwing state between the main body 12a and the screw hole 5g is loosened and the deflector 12 tries to come out of the suction / discharge port 5b, the outer end face of the deflector 12 abuts on the inner periphery of the snap ring 13. Therefore, the deflector 12 does not come out of the suction / discharge port 5b. The pressing force acting on the deflector 12 by the high-pressure fuel in the fuel pressurizing chamber 8 is applied to the screw surfaces of the main body 12a and the screw hole 5g even if the screwing is loose. Therefore, a large pressing force hardly acts on the snap ring 13, and the snap ring 13 only prevents its rotation by preventing the deflector 12 from moving outward.
[0016]
At both ends of the snap ring 13, engagement holes 13a are respectively formed. Each of the engagement holes 13a is for engaging a dedicated jig (not shown) for expanding and contracting the diameter, and the snap ring 13 can be easily expanded and contracted by engaging the jig with the engagement hole 13a. The snap ring 13 can be easily attached to and detached from the annular groove 5h, and can be easily inserted into and removed from the suction / discharge port 5b. The snap ring 13 having such an engagement hole 13a is defined in JIS B2804 of the Japanese Industrial Standard, and a snap ring having an appropriate dimension can be selected and used therefrom.
[0017]
As shown in FIG. 3, mounting holes 2a, 2a passing through the peripheral wall of the pump main body 2 are arranged and formed so as to face the suction / discharge ports 5b, 5b. The mounting hole 2a is set to have such a size that the deflector 12 and the snap ring 13 can pass through the inside thereof, and a jig for expanding and reducing the diameter of the snap ring 13 can be inserted from the outside. Of course, a hexagon wrench or a wrench with a hexagonal hole can also be inserted. Therefore, the deflector 12 and the snap ring 13 can be attached to and detached from the suction / discharge port 5b from outside the pump main body 2 with the barrel 5 attached to the pump main body 2.
[0018]
A second deflector 14 is detachably inserted into the mounting hole 2a, and is fixed to the pump body 2 by a bolt 15 serving as fixing means. The second deflector 14 seals the mounting hole 2a and protects the inner surface of the pump body 2 from the impact of the fuel ejected from the intake / discharge port 5b. A shock absorbing hole 14a is formed on the end face facing the. Instead of the second deflector 14, a sealing member that merely seals the mounting hole 2a may be used.
[0019]
When replacing the deflector 12 in the fuel injection pump 1 having the above configuration, the second deflector 14 is first removed. Next, the jig is inserted through the mounting hole 2a, and the snap ring 13 is removed. Thereafter, a hexagonal wrench is inserted through the mounting hole 2a, the deflector 12 is rotated, extracted from the suction / discharge port 5b, and taken out from the mounting hole 2a. When attaching a new deflector 12 to the suction / discharge port 5b, the procedure may be reversed.
[0020]
As described above, in the fuel injection pump 1 of the present invention, the snap ring 13 prevents the deflector 12 from coming out of the suction / discharge port 5b. The ring 13 can be easily attached to and removed from the suction / discharge port 5b. Therefore, the deflector 12 can be easily replaced. Moreover, by removing the second deflector 14 from the mounting hole 2a, the deflector 12 can be replaced with the barrel 5 attached to the pump body 2. Therefore, the replacement of the deflector 12 can be performed more easily and in a shorter time.
[0021]
Note that the present invention is not limited to the above embodiment, and can be appropriately modified.
For example, as for the deflector 12, another deflector having a different shape and structure may be used as long as it is screwed and fixed to the suction / discharge port 5b.
[0022]
【The invention's effect】
As described above, according to the present invention, an effect is obtained that the deflector can be easily replaced at the site where the fuel injection pump is installed.
By forming a mounting hole facing the suction / discharge port in the pump body and detachably mounting a sealing member or a second deflector in the mounting hole, the deflector can be replaced from outside the pump body without removing the barrel from the pump body. The effect that it can be performed is acquired.
[Brief description of the drawings]
FIG. 1 is an enlarged sectional view showing a main part of an embodiment of the present invention.
FIG. 2 is a view as viewed from an arrow X in FIG. 1;
FIG. 3 is a longitudinal sectional view showing the entire embodiment of the present invention.
[Explanation of symbols]
Reference Signs List 1 fuel injection pump 2 pump body 2a mounting hole 5 barrel 5b suction / discharge port 7 plunger 12 deflector 13 snap ring 13a engagement hole 14 second deflector (sealing member)

Claims (4)

A pump body, a cylindrical barrel mounted in the pump body, and a plunger slidably provided in the barrel, wherein the barrel is formed with a suction / discharge port penetrating a peripheral wall thereof. In a fuel injection pump in which a deflector is screwed and fixed to a suction / discharge port,
An annular groove is formed on the inner peripheral surface at the outer end of the suction / discharge port, and the outer peripheral portion of a C-shaped snap ring capable of expanding and contracting is removably fitted into the annular groove by expanding and contracting the snap ring itself. When the deflector comes out of the opening outside the suction / discharge port, the outer end face of the deflector abuts against the inner peripheral portion of the snap ring, so that the deflector rotates in the direction of exiting the suction / discharge port outward. A fuel injection pump characterized by being stopped . 2. The fuel injection pump according to claim 1, wherein engagement holes for engaging a jig for reducing a diameter of the snap ring are formed at both ends of the snap ring. A mounting hole penetrating the wall of the pump body facing the suction / discharge port is formed, and a sealing member for sealing the mounting hole is detachably attached to the mounting hole. 3. The fuel according to claim 1, wherein the size is set so that the deflector and the snap ring can pass through the jig, and the jig can be inserted from the outside. Injection pump. The fuel injection pump according to claim 3, wherein the sealing member is a second deflector.

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